Can't seem to get bone layers to make any sense.

Hi folks. I’m having trouble getting my head around using the Layers in the Relations panel of the Bone tab in Pose mode. All I can seem to get it to do, is make bones vanish from a given layer. For example, if I select a bone, and then click the group of layers to put it in another layer, it just disappears from the layer I chose. If I go back to the first layer, the bone reappears, but if I try to view the bones of the layer I just tried moving it to, it shows all bones except for the one I wanted to put in that layer.

As soon as I tried to change the layer of a bone, I remembered I was totally thrown by this the last time I tried to make an armature, 'cause the bone I tried moving just vanished as soon as I clicked another layer. At the moment, I have a bone that doesn’t seem to be on any layers, but if I select it from the outliner, it immediately switches to the layer I tried to put it on, but without actually showing the bone. If I switch back to the first layer (where it was before I tried changing its layer), then ithe bone appears back on the first layer. Other bones I’ve since tried moving seem to behave slightly differently, but the more I try to figure this out, the more confused I get.

Can someone please help 'cause the behaviour I see in my installation of Blender doesn’t appear to behave anything like how the Blender manual describes (it says it’s basically the same as the object layers which isn’t remotely true), and all the videos on YouTube just seem to be about something else entirely (some plugin, I assume).

OK, can anyone please tell me if they even get the same behaviour on ony versions of Blender? Here’s how to replicate it…

  1. Start a new Blend file (and, optionally, remove all objects for simplicity).
  2. Add a new Armature (Single Bone) to the scene and then switch to Pose Mode.
  3. Look tothe Properties window, switch to its Bone tab and scroll down to the Layers section of the Relations panel.
  4. Ensure the bone is deselected and click any of the layers to confirm that the bone is not also visible in any other layer.
  5. Switch back to the first layer, select the bone and enter Edit Mode.
  6. Extrude the tail of the bone (E,Z,1 for example) and then switch back to Pose Mode.
  7. Ensure that neither bone is selected, ad then check the bone layers again. You should now find that the first (root) bone is now on all layers despite never having told it to go anywhere.
  8. Go back to the first layer and simply select the second bone (do not do anything else with it).
  9. Now look at the layers again. The first bone appears to have been removed from all (except the first) layers, and the second bone has apparently been inserted into all of the other layers.

Note that during all of this apparent layer changing, the M key has not been used once to change which bones are in which layers.Is this
a bug or what? Does anyone else get this behaviour?

Easy to get confused here. Lots going on. Hopefully I got this right…

The layer boxes in the Bone > Relations panel puts the active bone in the layers you select.

The active object in Blender is the last one selected with a click (not circle or box select). When you unselect everything that last bone you selected is still the active object even though it is no longer selected. It will move to the layer(s) you select in this panel.

The Key M shortcut in 3Dview puts the selected bones in the layers you select… all the selected bones not just the active one.

The layer boxes in Armature > Skeleton > Layers are visibility toggles. Enable the layers you want to see. Bones that “disappeared” are sitting in layers with visibility disabled.

This panel also displays which layers have bones (a dot) and if the active bone is in there (an orange dot). Here you can see the behavior of the relations layers panel (moves the active bone) vs. the shortcut method (moves all selected bones).

Hope this helps. Why the relations panel only moves active bone I don’t know. Maybe a feature. One sure way to find out is to report it as a bug.

-LP

Wow. Thanks for the comprehensive and crystal clear response. This thing was driving me crazy 'cause the more I tried to figure it out, the less it seemed to make any sense.

As far as I can tell, this answers my question and any likely follow-up questions. Thanks Larry. :smiley: